This invention relates to an attachment for use in connection with a cutting apparatus, such as a band saw or the like, which is adapted for both supporting and moving a workpiece along a path of travel into contact with a blade when forming circles or other arcuate shapes from the workpiece.
In forming circles or other arcuate shapes from a square or rectangular workpiece, for example, it is necessary to utilize an attachment since conventional table saws such as a band saw are not designed expressly for this purpose. These attachments typically include a track of some type on which a movable slide mounting a centering pin is carried. In use, the workpiece is mounted on the slide through an aperture formed in the workpiece which receives the centering pin. The piece is moved into position for contact with the cutting means and is then manually rotated about the centering pin to form a circle, for example. Representative attachments are described in U.S. Pat. Nos. 2,696,230; 4,027,566; and 4,244,253.
Each of the representative devices in the art possesses a common limitation in that no means are provided for advancing the slide carrying the workpiece in predetermined increments into or out of engagement with the blade or cutting means. Consequently, the precision achievable in the rate of movement of the piece is dependent upon the manual dexterity of the operator who must both move the piece along the track while rotating the same to form a circle or alternatively to form other arcuate shapes using a template, for example. Manual feeding will generally cause binding of the blade since the workpiece is often advanced too rapidly. In addition, in forming products having arcuate shapes as part of an overall pattern, the precision needed in gradually advancing the piece to form the arcuate shape cannot be achieved generally.
A further limitation is possessed by devices equipped with a track and slide in that the slide must be locked in a predetermined and fixed position prior to fabricating circles of a preselected diameter. Consequently, all ability to move the piece into or out of engagement with the blade is lost entirely in this application. Therefore, disparately shaped and dimensioned workpieces must first be fashioned into the approximate dimensions of the finished product prior to placement on the centering pin with significant attendant losses in productivity.
It is therefore an object of the present invention to provide an attachment for use with band saws or the like which includes means for supporting and incrementally moving the workpiece along a path of travel into or out of engagement with a blade to more precisely control the cutting process, particularly when using a template to form arcuate shapes. It is also an object to provide a device which is effective for moving the workpiece as described but which also has the ability to provide precise circles of a predetermined diameter, even though each distinct workpiece is of a disparate shape or dimension.
It is also an object of the invention to provide an attachment which is laterally adjustable in order to accommodate varying blade widths.
It is an additional object of the invention to provide an attachment which may be extended away from a worktable on which it is mounted for use in forming relatively large circular objects.